"insomniac" in the noun sense
1. insomniac, sleepless person
someone who cannot sleep
"insomniac" in the adjective sense
1. insomniac, sleepless, watchful
experiencing or accompanied by sleeplessness
"insomniac old people"
"insomniac nights"
"lay sleepless all night"
"twenty watchful, weary, tedious nights"- Shakespeare
Source: WordNet® (An amazing lexical database of English)
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